1. Technical Field of the Invention
The present invention relates generally to automotive alternators and bearing covers. More particularly, the invention relates to an automotive alternator that includes a flexible bearing cover.
2. Description of the Related Art
In automotive alternators, rolling bearings are generally provided in bearing boxes and covered at axial ends thereof by bearing covers, so as to be protected from foreign matters, such as water and dust.
For example, Japanese Patent First Publication No. 2005-151728 discloses an automotive alternator, in which two bearing covers respectively cover opposite axial ends of a rear-frame-side rolling bearing. Specifically, each of the bearing covers is configured to include a disc portion, which is disposed in intimate contact with an inner ring of the rolling bearing, and a cylinder portion that is press-fitted on a rotary shaft of the alternator which is supported by the rolling bearing.
With the above configuration, it is required to secure a sufficient space for installation of each of the bearing covers in the alternator. However, depending on the alternator product type, it may be difficult to secure such a sufficient space, particularly, on the side of a pole core mounted on the rotary shaft.
Further, in case that there is formed a restriction portion in the rotary shaft, which is located between the pole core and the rolling bearing to restrict axial movement of the pole core, it may be possible to omit the cylinder portion of the bearing cover and nip only the disc portion of the same between the restriction portion of the rotary shaft and the rolling bearing, thereby fixing the bearing cover.
However, in such a case, since the bearing cover has a fixed width in the axial direction of the rotary shaft, it is necessary to adjust the axial width of the restriction portion of the rotary shaft depending on the alternator product type, thus increasing the manufacturing cost of the alternator.